1. Field of the Invention
The present invention relates to the structure of a plasma display panel, and to a manufacturing method therefor; and in particular to the structure of barrier ribs (partition walls) formed between address electrodes to define a plasma discharge space, and to a manufacturing method therefor.
2. Related Arts
As part of the structure of a surface discharge three-electrode plasma display panel, a pair of display electrodes are provided along a display line on a front glass substrate, and a plurality of address electrodes that are perpendicularly positioned relative to the display electrode pair are provided on a rear glass substrate. The two glass substrates are positioned facing each other and are sealed together with a discharge space between them. A portion whereat the display electrode pair and the address electrodes intersect is a display cell area. A discharge (an address discharge) is performed between the display electrodes and the address electrodes, and a wall charge that is generated by the discharge is employed to perform a sustained discharge between the display electrodes.
Partition walls (barrier ribs) made of insulating material are formed between the address electrodes in order to prevent the address discharge from exerting an undesirable influence on adjacent cells. Fluophors formed on the address electrodes and between the partition walls are irradiated by ultraviolet rays generated by the plasma discharge, and various colored light beams are emitted by the fluophors to provide a display.
FIGS. 6A and 6B are cross-sectional views of the essential portion showing a process employed for forming ordinary partition walls. As is described above, a plurality of address electrodes 7 are formed on a rear glass substrate 6, and a dielectric layer 10 is formed thereon by using screen printing to apply a glass paste layer and thereafter subjecting the layer to an annealing process. A partition wall layer 8, formed of a glass paste having a low melting point, is coated on the resultant structure by screen printing, and is dried. Then, a dry film made of photosensitive material is adhered thereto. Exposure and development is performed on the resultant structure so that dry film layers 11 remain in regions where partition walls are to be formed. The cross-sectional view of FIG. 6A shows this state.
In order to perform the patterning of a thick partition wall layer 8 composed of a dry glass paste, following this, as is shown in FIG. 6B, fine particles 13 of alumina or silica are forcefully expelled from an air nozzle 12 to remove the exposed portions of the partition wall layer 8 by etching. This is a widely known sandblasting procedure that can satisfactorily form a comparatively thick partition wall.
However, with the sandblasting procedure, when the particles are expelled and strike the partition wall layer 8, contact electrification occurs, so that the grains and the surface of the partition wall layer 8 acquire negative and positive charges, for example. As a result, as is shown in the cross-sectional view in FIG. 7, when the sandblasting procedure is terminated, some of the material used for partition walls, or some of the abrasive particles, remains as a residual substance 8a on the dielectric layer 10 covering the address electrodes 7.
It has been substantially confirmed that accumulation of the residual substance 8a is caused by contact electrification. However, precisely how contact electrification causes the residual substance 8a to accumulate on the address electrodes 7 is not yet known. But since the residual substance 8a mainly accumulates on the address electrodes 7, as is shown in FIG. 7, it is felt that a reaction between the electric charges acquired by the wall material and the abrasive particles and the electric potential of the address electrodes 7 causes the abrasion rates to differ.
When on a structure there is residual substance 8a remaining following the sandblasting procedure which is difficult to remove, and this structure and the front glass substrate are assembled together, the presence of the residual substance 8a causes the characteristics of the cells at the intersections of the display electrodes and the address electrodes to be ununiform.